1. Technical Field
The present invention relates to mobile wireless terminals, such as mobile phone terminals, and antenna devices thereof.
2. Description of the Related Art
Recently, the performance and the number of functions of mobile wireless terminals, such as mobile phone terminals, have been increased. Mobile wireless terminals are emerging that make wireless communication functions, such as functions of telephone communication, data communication, the global positioning system (GPS), a wireless local area network (LAN), and BLUETOOTH available.
One type of antenna for use in such wireless communication is a λ/4 monopole antenna including a plate and an antenna element having a length of a quarter of wavelength of a frequency to be used.
Japanese Unexamined Patent Application Publication No. 2009-225068 discloses a monopole antenna that produces circular or elliptically polarization with a combination of a feed element, a parasitic element, and a ground plate (i.e., a plate). More specifically, the feed element and the parasitic element are bent in an inverted L shape against the ground plate. The bent sides of the feed element and the parasitic element are disposed in different directions to form a truncated chevron with an angle θ. Transmission power is fed from a point between the feed element and the ground plate, whereas reception power is extracted at the point. The parasitic element is electrically connected to the ground plate. The length of the parasitic element is set to be equal to or smaller than that of the feed element.